Cut-out for incandescent electric lamps



(No Model.)

. T. A. EDISON. OUT-OUT FOR INGANDESCENT ELBGTRIG LAMPS. No. 426,762.Patented Apr. 15, 1890.

UNITED STATES PATENT OFFICE.

THOMAS A. EDISON, OF LIIEIVELLYN PARK, NEIV JERSEY.

CUT-OUT FOR INCANDESCENT ELECTRIC LAMPS.

SPECIFICATION forming part of Letters Patent No. 425,762, dated April15, 1890.

Application filed March 8, 1888. gerial No, 266,592. (No model.)

To all 1072,0111 it may concern:

Be it known that I, THOMAS A. EDISON, of Llewellyn Park, in the countyof Essex and State of New Jersey, have invented a certain new and usefulImprovement in Incandescent Electric Lamps, (Case No. 7 66,) of whichthe following is a specification.

In my application, Serial No. 241,959, filed June 21, 1887, is shown anddescribed a cut-out for incandescent electric lamps,in which a nor.-mally-idle Wire terminating in the vacuum between the sides of thecarbon loop holds out of action a spring contact-piece, and when thelamp breaks and an arc springs across the filament the excessive currentupon the said idle wire fuses the same, so that said contactpiece isreleased and completes a shunt-circuit around the lamp.

In the application referred to the short circuit was completed bybringing the contact piece into contact with the bottom plate of thesocket of the lamp.

The main object of the present invention is to so construct and arrangethe parts of a cutout of the same general character as that justdescribed that the same will be entirely contained in the lamp itself,so that the metal parts of the socket will not be required to form partof the cut-out apparatus.

In addition, my object is to increase the simplicity and effectivenessof cut-out arrangements of this kind.

My invention is illustrated in the accompanying drawing, which shows thelamp in elevation, with its insulating-base in section to show thecut-out which is within the same.

A is the glass vacuum-chamber of the lamp, which incloses the carbonfilament 13, secured to metal wiresa b, passing through and sealed inthe glass of the lamp at O. In the glass between the lamp-wires is alsosealed a piece of platinum wire 0, which extends up between theterminals of the filament, and whose lower end is formed into a book (1.

Upon the lower end of the lamp is secured the plastenof-paris base D,which holds the metal band'E and the screw-threaded collar or band F onthe outside of the base, and in a recess formed in the bottom, of thebase the metal band 6. The base is formed, as is now well understood,bypouring the plaster into a mold around thelamp-neck, which mold holdsthe bands E, F, and c, the wire I) having previously been soldered tothe band F, and the short connecting-wire f having also been soldered tothe bands F and c. The base is molded with an opening at g, extendingfrom above the band e through to the lamp-neck. After the base andterminals are thus in position the fine fusible wire 7L, preferably ofiron, with its end twisted into a loop or eye, is inserted in thelamp-neck through the opening 9 and hooked onto the hook (Z of platinumwire 0. Then upon the lower end of said wire is threaded a small spiralspring 1', and beneath it a conical metal button 7., with a hole for thewire in its center and by which the spring is compressed. These partsare then secured by a drop of solder at the center of button 75.

I11 molding the base it is formed with a circular groove at Z, and theend of the wire a is left projecting within or near this groove. A capG, forming the lower terminal of the lamp base, is placed with its edgesin the groove Z, and the wire a is soldered to said cap, whereby mainlythe cap is held in position, though I prefer to place at the exposedpart at a little asphalt or similar moisture-proof material, which willassist in sticking the cap G to the base.

It will be understood that when in use the lamp is screwed into a socketand the terminals F and G make contact with corresponding terminals inthe socket, whereby the circuit is completed through G a 12 F in the normal operation of the lamp.

The bandE furnishes a metal covering for the base, which may be graspedby the hand in placing the lamp in and withdrawing it from its socketwithout danger from the hightension current employed in series systems,said band being entirely insulated from all current-conveying parts.

The lamp being placed in series with other lamps, if the filamentbreaks, an are usually forms across the vacuum between the filamentterminals. When this occurs, the platinum wire 0 and fine iron wire 71which is 0011- nected with the circuit out-side the lamp, receive somuch current that said wire 7L is fused thereby, whereupon the spring isre leased, and the button 75 is forced. thereby down against theterminal G and connects it with band 6, whereby a shunt is completedaround the broken filament through G, button 7c, band 6, wire f, andband E.

What I claim is 1. In an incandescent electric lamp, the combination ofthe globe, the hollow base secured thereto, a stationary contact-pieceattached to said base and connected with one terminal of the lamp, amovable contact-piece within said base connected with the otherterminal, and a fusible wire attached to said movable contact-piece andextending from the interior of said globe and holding said movablecontact-piece normally out of contact with the stationary one, wherebythe lamp-filament is short-circuited by the fusion of said wire,substantially as set forth.

2. In an incandescent electric lamp, the combination of the globe, thebase having an opening through it, the bottom plate closing saidopening, the movable contact within said opening connected with thelamp-circuit, and the wire between the leading-in wires supporting saidcontact, substantially as set forth.

3. In an incandescent electric lamp, the combination of the globe, thebase having an opening through it, the plate closing said opening, themetal band within said opening connected with the lamp-circuit, themetal button sliding in said opening, and the wire between theleading-in wires supporting said button, substantially as set forth.

4. In an incandescent electric lamp, the combination of the globe, thebase having an opening through it, the bottom plate closing saidopening, the movable spring contact within said opening connected withthe lampcircuit, and the wire between the leading-in wires supportingsaid cont-act, substantially as setforth.

5. In an incandescent electric lamp, the combination, with the globe,the leading-in wires, and the filament, of the base having an openingthrough it, the plate closing said opening, to which one of theleading-in wires is connected, the screw-threaded band on said base, towhich the other leading-in wire is connected, the contact movable insaid opening and connected with said screw-threaded band, and the wiresituated between the leading-in wires and supporting said contact,substantially as set forth.

This specification signed and witnessed this 3d day of March, 1888.

THOS. A. EDISON.

lVitnesses:

- -WM. PELZER,

E. C. ROWLAND.-

